Austrolebias varzeae, Costa & Reis & Behr, 2004

Costa, Wilson J. E. M., Reis, Roberto E. & Behr, Everton R., 2004, Austrolebias varzeae, a new annual fish from the upper rio Uruguay basin, southern Brazil (Cyprinodontiformes: Rivulidae), Neotropical Ichthyology 2 (1), pp. 13-17 : 14-15

Austrolebias varzeae , new species

Fig. 1

Holotype. MCP 29641, male, 33.7 mm SL; Brazil: Rio Grande do Sul, temporary lagoon close to the rio da Várzea, Fazenda dos Branda , Carazinho , rio Uruguay basin, approximately 28º18’S, 52º48’W; M. N. Xavier, 26 Aug 1999.

Paratypes. MCP 23667, 7 males (1 c&s), 23.8-32.5 mm SL, and 2 females, 24.8-25.3 mm SL; UFRJ 5431, 1 male, 30.9 mm SL, and 1 female, 25.8 mm SL; UFRJ 5432, 1 male, 31.9 mm SL, and 1 female (c&s), 23.5 mm SL; all collected with holotype .

Diagnosis. Readily distinguished from all congeners by a unique color pattern of male, consisting of dark gray bars on

flank, the three anteriormost bars distinctively darker and narrower than posterior ones ( Fig. 1 ). It is similar to A. carvalhoi and distinguished from all other species of the genus by the combination of pattern of bars on male flank and autopalatine with a prominent dorsomedial projection. It differs from A. carvalhoi by having more anal-fin rays in male (23-26 vs. 21-22) and consequently a longer anal-fin base length (38.1-40.9 % SL vs. 31.4-35.1 % SL), and more caudalfin rays (28-29 vs. 25-26). Other features plesiomorphic for Austrolebias but useful to distinguish A. varzeae are the urogenital papilla of male not attached to anal fin, pelvic fins not united medially, 22-24 dorsal-fin rays in male and 16-18 in female, 18-19 anal-fin rays in female, and 28-30 scales in the longitudinal series.

Description. Morphometric data for holotype and seven paratypes given in Table 1 . Male larger than female, reaching at least 33.7 mm SL. Dorsal profile concave on head, convex between snout and end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile convex from lower jaw to end of anal-fin base, nearly straight on caudal peduncle. Longest body depth on vertical through dorsalfin origin. Body somewhat deep, compressed, body depth approximately 1.9 times body width in larger males. Snout blunt, jaw short.

Tip of dorsal and anal fins rounded. Anteromedian rays of anal fin of female not lengthened, anal fin shape approximately semicircular. Urogenital papilla of male not attached to anal fin. Caudal fin rounded. Pectoral fin elliptical, its posterior margin reaching vertical between pelvic-fin base and urogenital papilla in male, and reaching vertical through urogenital papilla in female. Tip of pelvic fin reaches base of second anal-fin ray. Pelvic-fin bases in close proximity, but fins not medially united. Dorsal-fin origin approximately on vertical through pelvic-fin base in male, and through urogenital papilla in female. Anal-fin origin on vertical through base of second or third dorsal-fin ray. Dorsal-fin rays 22-24 in male, 16-18 in female; anal-fin rays 23-26 in male, 18-19 in female; caudal-fin rays 28-29; pectoral-fin rays 12; pelvic-fin rays 5.

Scales large, cycloid. Body and head entirely scaled, except on ventral surface of head. Frontal squamation Fpatterned. No transverse row of scales on anal-fin base. Pectoral-fin base naked. Longitudinal series of scales 28-30, transverse series of scales 16-17, and scale rows around caudal peduncle 20. One discrete ctenii-like contact organ on each scale of ventral portion of body side of male. No contact organs on unpaired fins and outer surface of pectoral and pelvic fins. Rudimentary papillate contact organs on inner surface of three dorsalmost rays of pectoral-fin of male. Supraorbital neuromasts 15-22.

Jaw teeth gently bowed, with few larger fang-like teeth laterally. Slight concavity on anteromedial portion of premaxilla. Alveolar arm of premaxilla with prominent anterior process. Prominent rounded dorsomedial projection on autopalatine. Basihyal about triangular, its longest width about 80% of its total length; basihyal cartilage long, occupying about 65% of total basihyal length, and with pronounced lateral projections on its anterior portion. Anterior ceratohyal not elongated. Six branchiostegal rays. Urohyal deep. Three to five teeth on second pharyngobranchial. Gill-rakers on the first branchial arch 3+9. Lateral process of sphenotic narrow, without anterior expansion. Posterior arm of parasphenoid narrow. Lacrimal approximately straight in its dorsoventral axis. Dermosphenotic absent. Ventral process of posttemporal robust. Total vertebrae 27-28.

Etymology. Austrolebias varzeae is named after the river basin were it was collected, the rio da Várzea.

Figures

Fig. 1. Austrolebias varzeae, holotype, MCP 29641, male, 33.7 mm SL; temporary lagoon close to the rio da Várzea, rio Uruguay basin, Carazinho, Rio Grande do Sul, Brazil.